A digital video signal is characterized by picture format information and other associated parameters. Typically, the format of a video signal includes the spatial resolution of the picture, frame rate, and the bit-depth of samples (i.e., pixels), as well as the relational storage (or transmission) order of the samples corresponding to each of the three components of the digital video signal: the luma component (Y) and the chroma components, U and V. The spatial sampling arrangement of the three components in relation to each other is also part of the picture format information.
Digital video signals typically employ YUV components and conform to a 4:2:0 sampling arrangement with a relative ordering of its three components referred to as planar format. A digital video signal in YUV 4:2:0 planar format consists of all the samples of the Y component in raster scan order, followed by all the samples of the U component in raster scan order, followed by all of the samples of the V component in raster scan order. In planar format, each of the three components, Y, U, and V, can be indexed in storage by a respective pointer and processed independently and sequentially. The spatial resolution of a YUV digital video signal corresponds to the spatial resolution of the Y component. The spatial resolution of each of the respective chroma components of a YUV 4:2:0 digital video signal corresponds to half of the horizontal resolution of the Y component and half of the vertical resolution of the Y component. Since the total number of samples of each of the two chroma components of a picture is equal to one fourth of the total number of samples of the luma component, a YUV 4:2:0 picture results in an average of 1.5 samples per pixel.
Other associated parameters that characterize a digital video signal include the sample aspect ratio, the scan type of the pixels in each picture, the spatial offset (or location) of the chroma samples in relation to each corresponding set of 2 by 2 luma samples in each picture, information related to its opto-electrical transfer function, and colorimetry information.
Many video applications have traditionally employed digital video signals with samples of 8-bit resolution for each of the three components of each picture. In the aim for picture quality that is better than High Definition (HD) video signals, Ultra HD (UHD) video signals, also referred to as 4K video signals, typically have 10-bit samples (i.e., 10-bit samples in each of the three components of the digital video signal). Whereas 8-bit samples have been amenable to the traditional byte-aligned de facto digital world, processing video signals with 10-bit pixels creates new challenges.